40 INSECTICIDES AND FUNGICIDES. 



Table VI shows that the percentages of both moisture and ash are 

 about normal and fairly close together in samples 19528, 19529, 

 19559, 1967T, 20371, 20483, 20485, 20486, and 20487, with the exception 

 of 20371, in which the ash is rather high. This high ash content 

 might easily occur, however, in a sample that had not been tampered 

 with in any way. The ether extract figures for the above numbered 

 samples are much higher than those found by Hilgard for Buhach, 

 and the residue has a strong characteristic smell, indicating that the 

 samples are high in that active principle which kills insects. On the 

 whole, all of the above-mentioned samples appear to be the true pow- 

 dered pyrethrum flower. 



Sample 19530 is a bright yellow powder, which has a higher per- 

 centage of ash and a lower percentage of ether extract than the aver- 

 age. The oil obtained by extracting with ether has not a very strong 

 pyrethrum odor, and the presence of lead and chromium in the ash of 

 this sample shows that lead chromate has been added to give the pow- 

 cer a brighter yellow color. This sample appears to be either only 

 partially composed of the flower of pyrethrum, or composed of flowers 

 of an inferior quality or of flowers mixed with stems. The use of lead 

 chromate in powders of this class, which are to be blown out in the 

 air of a room, does not appear to us as commendable, since they are, 

 to a certain extent, breathed by human beings, and the lead chromate 

 contained might give rise to troubles more or less serious. 



MIXTURES CONTAINING BORAX. 



Practically all of these mixtures are used for the destruction of cock- 

 roaches and water bugs, and some are further advertised to kill fleas, 

 moths, ants, lice, etc. The substances contained in these compounds 

 are so many in number and the methods of analysis so diverse that 

 only the methods that are used for the determination of borax will be 

 given. Where there is no interfering substance the following method a 

 is used: 



METHODS OF ANALYSIS AND DISCUSSION.. 



Weigh 2 grams of the sample out into a 200 cc flask and shake 

 well with water till all borax is dissolved. Make up to the mark, filter 

 through a dry filter, throwing away the first 5 cc, and take aliquot 

 portions of 50 cc for analysis. Add methyl orange and then dilute 

 sulphuric acid drop by drop to the appearance of a pink color. Boil 

 to get rid of carbon dioxide, cool, add a little more methyl orange and 

 titrate back with fifth normal sodium hydroxid until the pink color 

 just changes to yellow. All boric acid is now in the free state. Add 



a Thomson. Button's Volumetric Analysis. 



